Are you talking about SCT Inst? It seems like there are no fees built into the protocol itself, but your bank can still charge you to use the service, and it seems many banks charge between 1 and 7 euros:
I didn’t mean a specific protocol, just based on my experience. But where do you see 7€ in this document? I see lot of banks offering zero or below 1€ fees. The highest I see is Novo Banco at 5.20€ (page 18).
(pdf reference) https://www.beuc.eu/sites/default/files/publications/beuc-x-...